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Discussion Starter #1
We've got a 2011 Cruze LT with about 80,000 miles. Recently, when started and sitting at idle, there's a repeating noise in the engine compartment. It repeats approximately every 2 seconds and SOUNDS somewhat like something activating then shutting off. I'd classify it as a "thrumming" sound. It's not loud, but it's audible when sitting IN the car and quite audible when the hood is open. It DOES NOT change in volume or speed as the engine speed changes. It doesn't appear to be a water pump or serpentine belt or anything specific to the front of the engine.

It's there when the vehicle is sitting in park, it doesn't change if the fan is on or off or if the A/C compressor is on or off. I's there when the vehicle is in gear at speeds low enough to hear.

Is there a pump that runs at intervals to drive the power steering? Something else in the engine bay that runs at intervals of 2 seconds or so?
 

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Evap purge solenoid maybe?

My old Mazda6S had a particularly loud purge solenoid. At extremely light throttle application and low speed it sounded like an engine knock. I tried remounting it on o-rings and using a leftover piece of Dynamat Extreme under the mount. It was just loud under those circumstances. Unplug it and the sound went away (and the CEL came on)
 

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We've got a 2011 Cruze LT with about 80,000 miles. Recently, when started and sitting at idle, there's a repeating noise in the engine compartment. It repeats approximately every 2 seconds and SOUNDS somewhat like something activating then shutting off. I'd classify it as a "thrumming" sound. It's not loud, but it's audible when sitting IN the car and quite audible when the hood is open. It DOES NOT change in volume or speed as the engine speed changes. It doesn't appear to be a water pump or serpentine belt or anything specific to the front of the engine.

It's there when the vehicle is sitting in park, it doesn't change if the fan is on or off or if the A/C compressor is on or off. I's there when the vehicle is in gear at speeds low enough to hear.

Is there a pump that runs at intervals to drive the power steering? Something else in the engine bay that runs at intervals of 2 seconds or so?
Hello GracieAllen,

We apologize for the recent concerns you seem to be experiencing in your Cruze. If you need any additional assistance communicating this with the dealership, we would be more than happy to look into this further for you. Feel free to send us a private message along with your VIN, current mileage, contact information and a preferred dealership.

Patsy G
Chevrolet Customer Care
 

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Discussion Starter #4
It's not a ticking or a knock. Closest thing I could come up with is it sounds somewhat like the noise wiper blades make. About that speed too. It doesn't change when turning the steering wheel. It DOES APPEAR to stop when I turn on the A/C. BUT, if it's something to do with the compressor clutch I presume the frequency would change with engine speed. It doesn't appear to change with engine speed......

Something with A/C compressor?
 

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Turning on the A/C changes the load on the belt. Changing electrical load also changes the load on the belt. So I'm wondering if there's any big electrical load that cycles like that.

Then again, belts can do strange things.
 

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Problems like this, have to be there, just way too many variables. First question is how does your Cruze idle, is it smooth and constant? So I don't have to rely on the tach, use my smart phone with Torque pro on it with a digital display.

Next step is to dig out my stethoscope, okay so its just a 3 foot length of heater hose, but helps to isolate where the noise id coming from. If any where near the belt drive system, remove the belt and just run the engine for a very short time or it will burn itself up.

Can emulate motor mount problems that can also reflect to the exhaust system but shaking that tiny 1.4L engine. Or slapping my hand, for all I know, a plastic wheel well can be loose. Ha, with some dealer work on my Cruze, they didn't replace all of my push pin plastic rivets, went back and said, where are my push pin rivets. Couldn't find them so had to order them.

My latest problem with just 36K on this thing, notice when I take my foot off the gas when I have to gun it to get on the interstate, the engine speed doesn't drop as fast as it use to, gas pedal is kicking back very quick. So has to be in the throttle vane sticking a bit.

This is not a new problem when they return the PCV hose back into the air inlet where it has to go through the TB first. The TB vane gets all this crap. Was not a problem when they returned the PCV hose to the intake manifold, but is now. That bypassed the TB.
 

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My 2011 seems to make the same noise, not all the time though like when you go to dealer nothing. Please keep us posted if find anything out.
 

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Discussion Starter #8
It idles fine, smooth and as constant as I can tell. Runs fine, has normal amount of "pep". I figure if it IS the A/C it has to be the clutch 'cause when the compressor is on the noise is gone. OR, I suppose it could be a serpentine belt with a nasty spot - although I don't see anything.

I was kind of hoping it'd be something obvious in here - "Oh, that's the framis rubbing the whosis" and I wouldn't have to take it in for the parts changers to mess with......
 

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Could write a book on this, some idiot at GM decided to use an interference fit on the clutch plate around 25 years ago instead of using shims for a proper clutch gap like everyone else is doing. That gap can either close like your is or open so your clutch doesn't engage at all. Should be 20 mils for this gap and requires a special tool for this.

So far I have three of these and think I need a forth for the Cruze because they keep on changing the threads. Wasn't so bad when the compressor was mounted on top of the engine, but an extra PITA where its located now. Have to jack up the right wheel, properly support it, remove the wheel and that plastic well. Ha, don't break any of those push pin rivets, dealer wants $4.86 for each of them.

On some GM vehicle, had to drop the compressor because there is no room for the tool. Do this very carefully without stressing the hoses, and securely wire it up. If you break those hoses, really big problems. Haven't done this on my Cruze yet, so don't know.

That compressor shaft may or may not have a nut on it, only there for safety so the clutch plate doesn't fly off, seen them both ways, but end up installing a nut if it doesn't have one. Then trying to start that nut inside the female threads that are a pile of rust. Soften those up first with PB blaster, then start the engine, engage the compressor and use a toothbrush like wire brush tool to clean this up first. Do this very carefully so you don't break your fingers or lose some. Then I can start that nut.

Has a bolt that screws that into that nut to pull the clutch plate out, but you find this takes a great deal of force because that plate is really rusted on. Do this very carefully because if you go out too far, will have to reverse the tool to push it back in again. You don't want to clean that rust off the shaft or will never get a good gripe, one location where rust is good.

Usually once you do this, don't have to ever do it again, that rust really holds that gap.

All this stupidity, because some idiot at GM can't use shims. So why do I keep on buying GM vehicles? I am the idiot.
 

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There have been known issues in 2011 models with the AC compressor clutch not disengaging entirely. Chevys fix was to replace the compressor entirely, but I do wonder if the clutch or solenoid can be replaced separately.

With the AC off, see if the suction line (big fat one with the charge port on it) leading into the compressor feels cool to touch - or has condensation on it.
 

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Ha, know of AC shops that really screw people on this subject, like your compressor has to be replaced hitting them with a 1,500 buck bill.

Easiest to learn if this it your problem is to get a feeler gauge and see if a 0.020: blade will fit in that gap between the idler pulley and the clutch plate.

Not a question of thinking, is a question of checking.
 

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Discussion Starter #12
Good grief. How many DECADES have they been putting A/C in cars? And they STILL haven't gotten it figured out so this kind of stupid <bleep> doesn't happen?
 
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